"Tatyana Titova, the director of Museum of Power" was detained at 2:00 am (3:30 am IST Tuesday), when she was hanging paintings in the museum," said the founder of the Saint-Petersburg privately-owned venue, Alexander Donskoi.
She was released from the police station four hours later without explanation, Donskoi told AFP.
Police a week ago Tuesday raided an exhibition at the Museum of Power, taking several paintings, including one where Putin appears in a strappy nightie while Medvedev is pictured in a bra and knickers.
Police in Saint Petersburg told Russian news agencies that Titova was never formally detained, but that policemen reacted to a call from a citizen worried about "suspicious people" in the neighbourhood.
"After checking documents, the people were let go at 6:00 am," a police representative told Interfax.